freedreno/ir3: fix ir3_nir_move_varying_inputs
ir3_nir_move_varying_inputs is broken when there a load input outside of
the first block which depends on the result of a previous load input.
This simplification/rework avoids the problem, and should also be faster.
Fixes this dEQP-VK test:
dEQP-VK.pipeline.multisample_interpolation.offset_interpolate_at_pixel_center.128_128_1.samples_2
Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5465>